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To profile a component of the current project, simply pass the --profile flag to stack. The --profile flag turns on the --enable-library-profiling and --enable-executable-profiling Cabal options and passes the +RTS -p runtime options to any testsuites and benchmarks.

For example the following command will build the my-tests testsuite with profiling options and create a file in the current directory as a result of the test run.

stack test --profile my-tests

The file now contains time and allocation info for the test run.

To create a profiling report for an executable, e.g. my-exe, you can command:

stack exec --profile -- my-exe +RTS -p

For more fine-grained control of compilation options there are the --library-profiling and --executable-profiling flags which will turn on the --enable-library-profiling and --enable-executable-profiling Cabal options respectively. Custom GHC options can be passed in with --ghc-options "more options here".

To enable compilation with profiling options by default you can add the following snippet to your stack.yaml or ~/.stack/config.yaml:

  library-profiling: true
  executable-profiling: true

Further reading

For more commands and uses, see the official GHC chapter on profiling, the Haskell wiki, and the chapter on profiling in Real World Haskell.


To generate a backtrace in case of exceptions during a test or benchmarks run, use the --trace flag. Like --profile this compiles with profiling options, but adds the +RTS -xc runtime option.

Debugging symbols

Building with debugging symbols in the DWARF information is supported by Stack. This can be done by passing the flag --ghc-options="-g" and also to override the default behaviour of stripping executables of debugging symbols by passing either one of the following flags: --no-strip, --no-library-stripping or --no-executable-stripping.

In Windows, GDB can be installed to debug an executable with stack exec -- pacman -S gdb. Windows' Visual Studio compiler's debugging format PDB is not supported at the moment. This might be possible by separating debugging symbols and converting their format. Or as an option when using the LLVM backend.